David Chiu, president of SF Board of Supervisors, who is also a classically trained violinist, playing with Lumaya, an alternative rock band playing at the Red Devil Lounge in San Francisco, Calif., on Friday, July 24, 2009.

Photo: Liz Hafalia, The Chronicle

David Chiu, president of SF Board of Supervisors, who is also a...

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San Francisco Board of Supervisors President David Chiu, left, and Mayor Gavin Newsom listen to a supervisor's speech after Chiu was elected president of the San Francisco Board of Supervisors in the board's San Francisco, Calif., chambers on Thursday Jan. 8, 2009..

Photo: Kim Komenich, The Chronicle

San Francisco Board of Supervisors President David Chiu, left, and...

Image 3 of 3

David Chiu, president of SF Board of Supervisors, who is also a classically trained violinist, playing with Lumaya, an alternative rock band playing at the Red Devil Lounge in San Francisco, Calif., on Friday, July 24, 2009.

By day - and even, let's face it, during the nights and weekends - David Chiu is busy working the levers of the city government as president of the San Francisco Board of Supervisors. So what does a municipal politician do to relax after a week packed with budget talks and committee meetings?

He pulls out his violin.

On Friday night, in a public appearance rather different from those connected with his day job, Chiu, 38, slapped an electric pickup on his violin and trooped down to the Red Devil Lounge to sit in with Lumaya, an alternative rock band made up of some of his longtime friends. It was not the kind of gig he was first trained to play.

"I was brought up strictly in the classical tradition - Bach, Mozart, Mahler," he said in an interview last week in his City Hall office. "To amplify your violin and go play in a venue where you're competing with a bass guitar and drums is a very different story."

Growing up in Boston as the child of Chinese immigrants who were both amateur musicians, Chiu started music lessons at a young age, beginning with the piano at 5.

"I had what was probably a typical reaction to the piano," he said, "I thought it was OK, but not the greatest thing in the world.

"But then when I was in third grade, my dad got me a half-size violin, pretty much on a whim, and I gravitated to it immediately. And that's when things really took off."

Throughout his high school years and into college, he says, playing the violin was his chief extracurricular pastime.

"I played for a ton of local orchestras, and I made money playing in pit bands and for weddings. The pinnacle of my young career was being named assistant principal second violin in the state youth orchestra."

But when Chiu got to Harvard - where he would ultimately earn an undergraduate degree, a law degree, and a master's degree in public policy - it quickly became clear that the violin would have to take a back seat.

"I'd had thoughts occasionally of a career in music. But I knew enough about that world, and what kinds of musicians were out there, to know that I couldn't really compete. I had friends who were going into a professional track, and they were all a cut above me.

"Also, I started getting much more involved in campus activism, and at the same time my parents were very concerned that I focus my energies on school. So I had to put the violin aside for a while."

These days, Chiu has the sort of on-again, off-again relationship with his instrument that characterizes so many one-time musicians with demanding full-time jobs.

He gets together with friends now and again to sight-read through string quartets, and he plays the occasional rock gig. But for the most part, the violin sits in its case, waiting for an opening in Chiu's schedule. When he ran for Supervisor in November, he says, he promised himself that if he lost the election he would go back to practicing regularly.

Still, Chiu likes to think that some of the legacies of his musical training have carried over into his political career.

"Obviously, playing the violin was how I first learned to do anything in public, so that was certainly helpful. But more importantly, as someone who was never good enough to be even a semi-regular soloist, I had to learn about how to play with others and make music together.

"Sometimes I think that as president of the board, my job is to bring the disparate voices together when everyone's trying to play their own melodies. It may not always by harmonious, but we do make our own kind of music here at City Hall."